Prince Carl Gustaf was the youngest of five children and the only son of Sweden's Prince Gustaf Adolf and Princess Sibylla. His father's death had left the nine-month-old Prince second in line for the throne, behind his grandfather, then Crown Prince Gustaf Adolf. When his great-grandfather Gustaf V died in 1950, the four-year-old Prince became the heir apparent of Sweden.

The young Crown Prince Carl Gustaf was seven years old before he was told about his father's death, and he expressed his feelings about growing up without knowing his father in a speech in 2005.

The 15-year old Crown Prince of Sweden looks at the recently recovered 17th century warship Vasa in 1961.

On 15 September 1973, Carl Gustaf became King of Sweden upon the death of his grandfather, King Gustaf VI Adolf. He was invested as King, at the Hall of State of the Royal Palace of Stockholm on 19 September 1973. King Gustaf VI Adolf was the last who used the style "By the Grace of God King of the Swedes, the Goths/Geats and the Wends" (med Guds Nåde Sveriges, Götes och Wendes Konung; Latin: Dei Gratia Suecorum, Gothorum et Vandalorum Rex). This traditional title had been in use since the establishment of the hereditary monarchy in 1544. Carl XVI Gustaf instead chose the plain and simple title "King of Sweden" (Sveriges Konung), thereby ending a centuries-old tradition.[1]

Such innovations are reflected in his personal motto, "For Sweden – With the times"[2] (För Sverige – i tiden).[3]

In the 16th century, Johannes Magnus construed a mythical line of Swedish kings, beginning with Magog, the son of Japheth, in an attempt to substantiate the antiquity of the Swedish throne. Based on that list, King Charles IX (reigned 1604 to 1611) adopted an ordinal not much supported by any accurate historical sources. Previous monarchs named Charles (Karl in Swedish) have traditionally been numbered by counting backwards from Charles IX, and subsequent monarchs by counting forward from him, though there were only two before him. Thus the current King of Sweden proclaimed himself Carl XVI Gustaf even though he is only the tenth Swedish monarch by the first name.[4]

The King and Queen of Sweden welcomed at the Kremlin by Russian Federation President Vladimir Putin and his wife Lyudmila at the start of the King's State Visit to Russia, 8 October 2001.

The King's duties are, according to the 1974 Instrument of Government, only of a representative and ceremonial nature. The 1974 document stripped the King of most of his formal political powers while retaining him as head of state, thus codifying actual practices dating from the definitive establishment of parliamentary government in 1917. Previously, the King formally appointed the Prime Minister, though in practice he was almost always the leader of the majority party or coalition in the Riksdag. Since the adoption of the current Instrument, that prerogative is now exercised by the Speaker of the Riksdag on the behalf of the Riksdag. Additionally, bills passed by the Riksdag do not need his signature to become law.

He pays State Visits abroad and receives those to Sweden, opens the Annual Session of the Riksdag, chairs the Special Council held during a change of Government, holds regular Information Councils with the Prime Minister and the Cabinet, chairs the meetings of the Foreign Affairs Council, and receives Letters of Credence of foreign ambassadors to Sweden and signs those of Sweden to foreign nations. As this type of figurehead, he also voluntarily abstains from voting in Swedish elections.[5]

King Carl Gustaf (ceremonially) holds the highest ranks in the three branches of the Swedish Armed Forces; this is due to the fact that he was, as stipulated by the 1809 Instrument of Government in effect at the time of his accession to the throne in 1973, the Commander in Chief of the armed forces of Sweden (§ 14) and therefore he was promoted ex officio from his earlier ranks of captain and lieutenant, to general and admiral. Under the provisions of the Instrument of Government of 1974, which became effective on 1 January 1975, King Carl Gustav no longer holds this constitutionally-mandated position of commander-in-chief, but he kept his ranks à la suite since he no longer has any military command authority, except over his military staff at his court.

The King is passionate about the environment, technology, agriculture, trade, and industry. Like many members of the Swedish royal family, the King has a keen interest in automobiles. He owns several Porsche 911s – a car model which is said to be a particular favourite of the King – as well as a vintage Volvo PV444, a Ferrari 456M GT, an authentic AC Cobra and other cars.[6] The first pictures taken of him and his future wife were of them sitting in his Porsche 911. In the summer of 2005 he was involved in a traffic accident in Norrköping. The accident was described as a "fender bender", with no serious personal injuries claimed. Nevertheless, the incident caused national headlines.[7]

The King is the Honorary Chairman of the World Scout Foundation, and often participates in Scout activities both in Sweden and abroad. He regularly visits World Scout Jamborees, for instance the 1979 Dalajamb World Jamboree International Encampment hosted by Sweden, the 2002 World Jamboree held in Sattahip, Thailand, and the 100th Anniversary of World Scouting 2007 World Jamboree held in Hylands Park, England.[8] He also attended the 1981 National Scout Jamboree in Virginia, United States, and was awarded the Bronze Wolf, the only distinction of the World Organization of the Scout Movement, awarded by the World Scout Committee for exceptional services to world Scouting, in 1982. He also attended the 22nd World Scout Jamboree. He gave a speech on 6 August 2011 at the closing ceremony with more than 40,000 people watching. The band Europe also performed for him singing "The Final Countdown". King Carl Gustaf made an appearance at the 2013 Boy Scouts of America National Jamboree in West Virginia.[9]

Prince Carl Philip was born the heir apparent. However, a constitutional reform, which was already under way at the time of his birth, made his older sister, Victoria, the heir apparent and Crown Princess of Sweden on 1 January 1980, according to the principles of absolute primogeniture, which Sweden was the first recognized monarchy to adopt.[12] King Carl Gustaf objected after the reform, not to the succession by females but to the fact that his son lost the position and title which he had had since birth.[13]

The Regal Assurance taken by His Majesty King Carl XVI Gustaf on 19 September 1973

Administered by Mr. Lennart Geijer, Councillor of State and Head of the Ministry for Justice

Unofficial English language translation

"We, Carl Gustaf, King of Sweden make known: that as our Supreme God has pleased to call away the formerly Mighty, High-Born Prince and Lord, Gustaf VI Adolf, King of the Swedes, the Goths and the Wends, and We, according to, and by authority of, the Act of Succession, as established and enacted by the Estates of the Realm on 26 September 1810, following the Illustrious Lord, have ascended to the Royal Swedish Throne.

Therefore We assure most solemnly and loudly, that We intend to, and shall, Govern the Realm in accordance with the on 6 June 1809 by the King and the Estates of the Realm, jointly enacted, and for observance issued, Instrument of Government, literal direction abide, and to the other Fundamental Laws of the Realm, public laws and legal ordinances.

We shall also conform to the before mentioned Instrument of Government and laws, as a resolute King and a caring father for the Swedish people, throughout a legal, just and lenient Reign, seek to by Our utmost ability to advocate the veritable interests and welfare of the Realm and that of each of its inhabitants, all of which We by free will and following mature consideration have decided to do, We thus confirm this by the written signature of Our Name, and by a lively oath, that this We shall adhere to and carry out, so truly help me God to life and mind."

* prince through adoption or election
** also prince of Norway
^lost his title due to an unequal marriage
#also prince of Poland and Lithuania
~Prince of Sweden by birth and marriage
*** Prince of Sweden by marriage only